Hub-less and nut-less turbine wheel and compressor wheel designs and installation/removal tool

ABSTRACT

A forced induction device for an internal combustion engine is provided, which includes a shaft, and a compressor wheel that is threadably mounted to the shaft, and a tool that is configured to engage one or more through bores in the compressor wheel to thread and unthread the compressor wheel onto and off of the shaft. The compressor wheel has a plurality of blades with leading edges that converge at an apex. The apex is aligned with a centerline of the shaft. The tool allows a technician to rotate the compressor wheel relative to the shaft to install or remove the compressor wheel from the shaft without applying any pressure to the blades of the compressor wheel. An associated assembly method is also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation-in-part application of U.S. patent applicationSer. No. 16/710,798, which was filed on Dec. 11, 2019, which is acontinuation-in-part of U.S. patent application Ser. No. 16/413,952, nowU.S. Pat. No. 10,914,231, which was filed on May 16, 2019 and claims thebenefit of U.S. Provisional Application No. 62/720,212, filed on Aug.21, 2018. The entire disclosures of the above applications areincorporated herein by reference.

FIELD

The subject disclosure generally relates to forced induction devices forinternal combustion engines, such as turbochargers and superchargers.More particularly, improved turbine/exhaust wheel and compressor/intakewheel designs are disclosed, which improve fluid flow to increasehorsepower without changing the wheel diameter or geometry.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may not constitute prior art.

Forced induction devices, such as turbochargers and superchargers,increase the efficiency and power output of an internal combustionengine by forcing extra air into the combustion chamber compared tonaturally aspirated engines. Turbochargers and superchargers are used ina wide variety of internal combustion engines, including gas, diesel,alcohol, and methanol fueled engines, to increase intake air flow with aresulting horsepower gain/advantage.

There remains a need for improvements to forced induction devices,including quicker spool-up, lighter weight, and increased air andhorsepower output. This is particularly true for engines used in highperformance motorsports including sled pulling, street racing, and dragracing, where high engine speeds and high boost applications are desiredand where rules and regulations are often in place that limit the sizeof the forced induction devices fitted to high performance motors.

Traditional forced induction devices often include compressor and/orturbine wheels with tool interfaces that obstruct the airflow throughthe device to some extent. For example, traditional turbochargers have alarge hex nut (or other style nut or fastener) on both thecompressor/intake wheel and turbine/exhaust wheel. This feature, whichis incorporated into the “hub” of the compressor/intake wheel andturbine/exhaust wheel, is used during the manufacturing process for manypurposes (holding, fastening, tightening, etc.). For example, the hexnut can be used as a clamping device when assembling the turbocharger,during machining operations, and/or during welding processes. Afterassembly, this hex nut provides no functional purpose to the operationof the turbocharger. The compressor wheels of centrifugal superchargerstypically have similar features.

SUMMARY

This section provides background information related to the presentdisclosure and is not necessarily prior art.

In accordance with one aspect of the subject disclosure, a forcedinduction device for an internal combustion engine is provided. Theforced induction device includes a compressor wheel threadably mountedto a shaft. The shaft is rotatable with respect to a housing and definesa centerline. The compressor wheel has a plurality of blades withleading edges that converge at an apex. The apex is aligned with thecenterline.

In accordance with another aspect of the subject disclosure, thecompressor wheel includes a body that extends along the centerlinebetween a leading end and a trailing end. The body has an outercircumference that is radially spaced from the centerline by acompressor radius. The plurality of compressor blades are positioned onthe body of the compressor wheel. The compressor apex is located at theleading end of the body and is aligned with the centerline of the bodyof the compressor wheel.

In accordance with another aspect of the subject disclosure, thecompressor wheel includes one or more through bores that extend throughthe compressor wheel at locations that are offset from the centerline ofthe shaft. A tool is provided with one or more posts that are configuredto be received in the through bores of the compressor wheel in a slidingfit. As such, the tool allows the compressor wheel to be rotated andthreaded onto the shaft during a compressor wheel installation processand unthreaded from the shaft during a compressor wheel removal processwithout applying pressure to the compressor blades, which can bend,chip, crack, or break if excessive pressure is applied.

In accordance with another aspect of the subject disclosure, a method ofconstructing a forced induction device is provided. The method includesthe steps of: machining a compressor wheel having a plurality ofcompressor blades, creating leading edges on the plurality of compressorblades, and performing a finishing operation on the compressor wheel toform an apex where the leading edges converge.

The method further includes the step of temporarily locking thecompressor wheel in rotation with a tool that includes one or more poststhat are received in one of more through bore in the compressor wheel.The method also includes the step of mounting the compressor wheel to ashaft by inserting the shaft into an internally threaded bore in thecompressor wheel and rotating the compressor wheel relative to the shaftin a first direction using the tool to thread the shaft into theinternally threaded bore of the compressor wheel.

The nut and/or the nose of the hub on traditional turbine and compressorwheels creates a disturbance in the flow pattern and flow volume of thefluid passing through the turbine and the compressor. This limitshorsepower potential. To increase power output, manufacturers typicallyup-size the frame of the turbocharger or supercharger. The presentdisclosure advantageously allows for increased power output andefficiency while using the same frame size by eliminating thenut/fastener/hex on the nose of the hub. The strength of the blades doesnot lie within the center of the hub/shaft so removing thenut/fastener/hex on the nose of the hub does not compromise thestructural integrity of the turbine wheel or the compressor wheel.

The designs set forth herein thus provide greater horsepower output andthrottle response by modifying the compressor/intake and turbine/exhaustwheels either in conjunction with each other or independently. Theelimination of the large hex nut on the hub decreases weight,back-pressure, increases spool-up speed, increases wheel blade length,and alters wheel blade geometry. The flow obstruction created by the hexnut is eliminated to maximize fluid flow and blade length, which cansignificantly increase horsepower by 10 to 75 percent over conventionalfastener nosed hub designs. In addition, the forced induction devicesdescribed herein provide improved serviceability because the compressorwheel can be installed on and/or removed from the shaft without applyingpressure to the compressor blades, which can bend, chip, crack, or breakif wrenched upon.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated,as the same becomes better understood by reference to the followingdetailed description when considered in connection with the accompanyingdrawings wherein:

FIG. 1 is a perspective view of an exemplary turbocharger;

FIG. 2 is a side elevation view of a traditional turbine/exhaust wheelfor the turbocharger shown in FIG. 1;

FIG. 3 is a front elevation view of the traditional turbine/exhaustwheel shown in FIG. 2;

FIG. 4 is a side elevation view of an exemplary nose-lessturbine/exhaust wheel for the turbocharger shown in FIG. 1 where theexemplary nose-less turbine/exhaust wheel has been constructed inaccordance with the teachings of the present disclosure;

FIG. 5 is a front elevation view of the exemplary nose-lessturbine/exhaust wheel shown in FIG. 4;

FIG. 6 is a side elevation view of a traditional intake/compressor wheelfor the turbocharger shown in FIG. 1;

FIG. 7 is a side section view of the traditional intake/compressor wheelshown in FIG. 6;

FIG. 8 is a front elevation view of the traditional intake/compressorwheel shown in FIG. 6;

FIG. 9 is a side elevation view of an exemplary nose-lessintake/compressor wheel for the turbocharger shown in FIG. 1 where theexemplary nose-less intake/compressor wheel has been constructed inaccordance with the teachings of the present disclosure;

FIG. 10 is a side section view of the exemplary nose-lessintake/compressor wheel shown in FIG. 9;

FIG. 11 is a front elevation view of the exemplary nose-lessintake/compressor wheel shown in FIG. 9;

FIG. 12 is a front elevation view of another exemplary nose-lessintake/compressor wheel;

FIG. 13 is a front perspective view of an exemplary intake/compressorwheel and backing plate sub-assembly of the turbocharger shown in FIG.1;

FIG. 14 is a front perspective view of an exemplary intake/compressorwheel and a corresponding installation/removal tool, which have beenconstructed in accordance with the teachings of the present disclosure;

FIG. 15 is a front elevation view of another exemplary nose-lessintake/compressor wheel; and

FIG. 16 is a front perspective view of another exemplaryintake/compressor wheel and another installation/removal tool, whichhave been constructed in accordance with the teachings of the presentdisclosure.

DETAILED DESCRIPTION

Referring to the Figures, wherein like numerals indicate correspondingparts throughout the several views, a forced induction device isillustrated for use with an internal combustion engine (not shown). Inthe Figures, the forced induction device is depicted as a turbocharger20, for illustration purposes. However, it should be appreciated thatthe teachings of the present disclosure also apply to other forcedinduction devices, including without limitation, centrifugalsuperchargers.

Example embodiments are provided so that this disclosure will bethorough, and will fully convey the scope to those who are skilled inthe art. Numerous specific details are set forth such as examples ofspecific components, devices, and methods, to provide a thoroughunderstanding of embodiments of the present disclosure. It will beapparent to those skilled in the art that specific details need not beemployed, that example embodiments may be embodied in many differentforms and that neither should be construed to limit the scope of thedisclosure. In some example embodiments, well-known processes,well-known device structures, and well-known technologies are notdescribed in detail.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “a,” “an,” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The terms “comprises,” “comprising,” “including,” and“having,” are inclusive and therefore specify the presence of statedfeatures, integers, steps, operations, elements, and/or components, butdo not preclude the presence or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. The method steps, processes, and operations described hereinare not to be construed as necessarily requiring their performance inthe particular order discussed or illustrated, unless specificallyidentified as an order of performance. It is also to be understood thatadditional or alternative steps may be employed.

When an element or layer is referred to as being “on,” “engaged to,”“connected to,” or “coupled to” another element or layer, it may bedirectly on, engaged, connected or coupled to the other element orlayer, or intervening elements or layers may be present. In contrast,when an element is referred to as being “directly on,” “directly engagedto,” “directly connected to,” or “directly coupled to” another elementor layer, there may be no intervening elements or layers present. Otherwords used to describe the relationship between elements should beinterpreted in a like fashion (e.g., “between” versus “directlybetween,” “adjacent” versus “directly adjacent,” etc.). As used herein,the term “and/or” includes any and all combinations of one or more ofthe associated listed items.

Although the terms first, second, third, etc. may be used herein todescribe various elements, components, regions, layers and/or sections,these elements, components, regions, layers and/or sections should notbe limited by these terms. These terms may be only used to distinguishone element, component, region, layer or section from another region,layer or section. Terms such as “first,” “second,” and other numericalterms when used herein do not imply a sequence or order unless clearlyindicated by the context. Thus, a first element, component, region,layer or section discussed below could be termed a second element,component, region, layer or section without departing from the teachingsof the example embodiments.

Spatially relative terms, such as “inner,” “outer,” “beneath,” “below,”“lower,” “above,” “upper,” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. Spatiallyrelative terms may be intended to encompass different orientations ofthe device in use or operation in addition to the orientation depictedin the figures. For example, if the device in the figures is turnedover, elements described as “below” or “beneath” other elements orfeatures would then be oriented “above” the other elements or features.Thus, the example term “below” can encompass both an orientation ofabove and below. The device may be otherwise oriented (rotated 90degrees or at other orientations) and the spatially relative descriptorsused herein interpreted accordingly.

With reference to FIGS. 1 and 2, the turbocharger 20 includes a housing22, a shaft 24, a turbine wheel 26, and a compressor wheel 28. The shaft24 has an outer surface 29 and is rotatable with respect to the housing22 and defines a centerline 30. Both the turbine wheel 26 and thecompressor wheel 28 are mounted to the shaft 24. The shaft 24 may be aone-piece shaft 24, or alternatively may be split into multiplesegments, such as a turbine segment and a compressor segment. The shaft24 may optionally include a threaded end 31. The housing 22 includes aturbine section 32 and a compressor section 34. A bearing pack 35 ispositioned between the turbine and compressor sections 32, 34 of thehousing 22 for rotatably supporting the outer surface 29 of the shaft24. The turbine section 32 of the housing 22 includes an exhaust inlet36 that is radially spaced from the centerline 30 and an exhaust outlet38 that is aligned with the centerline 30. The exhaust inlet 36 and theexhaust outlet 38 are configured to bolt to portions of the exhaustsystem of the internal combustion engine (not shown). Exhaust gasesenter the housing 22 through the exhaust inlet 36 and exit the housing22 through the exhaust outlet 38. The turbine wheel 26 is disposed inthe turbine section 32 of the housing 22 and includes a plurality ofturbine blades 40 with leading edges 42 that face the exhaust outlet 38.The flow of exhaust gas pushes against the turbine blades 40, whichdrives rotation of the turbine wheel 26.

The compressor section 34 of the housing 22 includes an air inlet 44that is aligned with the centerline 30 and an air outlet 46 that isradially spaced from the centerline 30. The air inlet 44 is configuredto receive air from the surrounding environment either directly orthrough an intake system (not shown). The air outlet 46 is configured tobe connected to an intake manifold of the internal combustion engine viaan inlet conduit (not shown), which may optionally include anintercooler (not shown). The compressor wheel 28 is disposed in thecompressor section 34 of the housing 22 and includes a plurality ofcompressor blades 48 with leading edges 42′ that face the air inlet 44.Rotation of the turbine wheel 26 drives rotation of the compressor wheel28 via the shaft 24. The compressor blades 48 pump air through thecompressor section 34 of the housing 22 as the compressor wheel 28rotates and discharge the air through the air outlet 46 at a higherpressure (boost) for delivery to the internal combustion engine.

With additional reference to FIG. 3, typical turbine or exhaust wheels50 (used interchangeably herein) are generally manufactured using hightemperature alloys (e.g., Inconel) to withstand the heat and pressurethat turbine or exhaust wheels 50 are exposed to by the exhaust flowingthrough the turbine section 32 of the turbocharger housing 22. Typicalexhaust temperatures at the exhaust inlet 36 of a turbocharger 20 rangefrom 1,000 to 2,000 degrees Fahrenheit. Turbine or exhaust wheels 50 aremanufactured either by casting or machining a forged alloy. Duringmanufacturing, a hub 52 is used as a means to hold or clamp the turbineor exhaust wheel 50 in place. For example, the hub 52 is used to holdthe turbine or exhaust wheel 50 when it is fused or friction welded tothe shaft 24. The hub 52 is generally large and left in place throughoutthe manufacturing process, the finishing process, and the finalturbocharger assembly process. The hub 52 on traditional turbine orexhaust wheels 50 obstructs fluid flow through the turbine section 32 ofthe housing 22 and therefore limits the horsepower potential of theturbocharger 20.

In accordance with the subject disclosure, the hub 52 on the turbine orexhaust wheel 50 is removed and/or eliminated and the turbine blades 40are re-shaped to an optimal geometry to create turbine wheel 26 (seeFIGS. 4 and 5). This change decreases weight, increases surface area,provides increased exhaust-to-blade contact and therefore increases theefficiency and power output of the turbocharger 20. Removing the hub 52and manipulating the fluid flow provides a significant horsepowerincrease and efficiency advantage for all turbochargers.

With reference to FIGS. 4 and 5, the turbine wheel 26 of theturbocharger 20 includes a turbine body 54 that extends along thecenterline 30 between a leading end 56 and a trailing end 58. Theturbine body 54 has an outer circumference 60 that is radially spacedfrom the centerline 30 by a turbine radius 62. The turbine blades 40 arepositioned on the turbine body 54. The turbine blades 40 have leadingedges 42 that converge at a turbine apex 64 located at the leading end56 of the turbine body 54. The turbine apex 64 is aligned with thecenterline 30. The leading edges 42 of the turbine blades 40 extendhelically from an inboard point 66 to an outboard point 68. In oneconfiguration, the inboard points 66 of the leading edges 42 touch oneanother and form a pointed shape at the turbine apex 64. In anotherconfiguration, the inboard points 66 of the leading edges 42 arepositioned closer to the centerline 30 than the smallest radius 69 ofthe shaft 24. In other words, the inboard points 66 of the leading edges42 are positioned within an imaginary circle 70 drawn around thecenterline 30 that has a radius 71 equal to the smallest radius 69 ofthe shaft 24. The imaginary circle 70 therefore coincides with the outersurface 29 of the shaft 24 and the inboard points 66 of the leadingedges 42 are positioned either on the centerline 30 itself or radiallybetween the centerline 30 and the imaginary circle 70.

With reference to FIGS. 6-8, typical compressor or intake wheels 72(used interchangeably herein) are generally cast or machined out of asolid forging (i.e., aluminum, titanium, etc.). The compressor or intakewheel 72 has a nut 74 (hub) at its center-point. This nut 74 is used inthe final assembly process and/or when building or servicing theturbocharger 20. The nut 74 on the compressor or intake wheel 72 is usedto secure the compressor or intake wheel 72 to the shaft 24 during finalassembly. This nut 74 also creates an obstruction to airflow and limitsthe horsepower potential of the turbocharger 20, especially in racing orhigh horsepower, high rpm, high engine speed (i.e., high rpm), and highboost applications.

In accordance with the subject disclosure, the nut 74 on the compressoror intake wheel 72 is removed and/or eliminated and the compressorblades 48 are re-shaped to an optimal geometry to create compressorwheel 28.

With reference to FIGS. 9-11, the compressor wheel 28 of theturbocharger 20 includes a compressor body 76 that extends along thecenterline 30 between a leading end 56′ and a trailing end 58′. Thecompressor body 76 has an outer circumference 60′ that is radiallyspaced from the centerline 30 by a compressor radius 78. The compressorblades 48 are positioned on the compressor body 76. The compressorblades 48 have leading edges 42′ that converge at a compressor apex 80located at the leading end 56′ of the compressor body 76. The compressorapex 80 is aligned with the centerline 30. The leading edges 42′ of thecompressor blades 48 extend helically from an inboard point 66′ to anoutboard point 68′. In one configuration, the inboard points 66′ of theleading edges 42′ touch one another and form a pointed shape at thecompressor apex 80. In another configuration, the inboard points 66′ ofthe leading edges 42′ are positioned closer to the centerline 30 thanthe smallest radius 69 of the shaft 24. In other words, the inboardpoints 66′ of the leading edges 42′ are positioned within an imaginarycircle 70′ drawn around the centerline 30 that has a radius 71′ equal tothe smallest radius 69 of the shaft 24. The imaginary circle 70′therefore coincides with the outer surface 29 of the shaft 24 and theinboard points 66′ of the leading edges 42′ are positioned radiallybetween the centerline 30 and the imaginary circle 70′.

Alternative configurations for attachment of the compressor wheel 28 tothe shaft 24 are provided, where a set screw 82, such as a hex screw,Allen screw, or similar style through-bore fastener, is threaded intothe compressor wheel 28. The nut 74 is eliminated and therefore does notinterfere with airflow. This provision decreases weight, increasespotential horsepower, air-flow, boost pressure, and compressor speed.

In the illustrated examples, both the turbine wheel 26 and thecompressor wheel 28 have a plurality of blades 40, 48 with leading edges42, 42′ that converge at apexes 64, 80 that are aligned with thecenterline 30. However, it should be appreciated that otherconfigurations are possible where only the turbine wheel 26 is providedwith an apex 64 or where only the compressor wheel 28 is provided withan apex 80. The apexes 64, 80 may be formed by either removing the hexnut 74, hub 52, or other manufacturing fixture from the leading ends 56,56′ of the turbine or exhaust wheel 50 and/or the compressor or intakewheel 72 prior to assembly or by eliminating the hex nut 74, hub 52, orother manufacturing fixture altogether from the manufacturing process.Regardless, the turbine wheel 26 and/or the compressor wheel 28 in finalassembled form have a nut-less/hub-less configuration, meaning thatthere is no nut 74 or hub 52 adjacent to the leading ends 56, 56′ of theturbine wheel 26 and the compressor wheel 28.

Although other configurations are possible, in the illustrated example,the turbine wheel 26 is welded to the shaft 24 while the compressorwheel 28 is attached to the shaft 24 by a threaded connection 84 and setscrew 82 (shown in FIG. 10). The compressor wheel 28 includes athrough-bore 86 with multiple stepped portions 88, 90, 92. The firststepped portion 88 has a smooth, cylindrical shape and receives aportion of the shaft 24. The second stepped portion 90 is threaded andthreadably engages the threaded end 31 of the shaft 24. The thirdstepped portion 92 is also threaded and threadably engages the set screw82. The third stepped portion 92 has a diameter that is smaller than adiameter of the second stepped portion 90 and the diameter of the secondstepped portion 90 is smaller than a diameter of the first steppedportion 88. The threads in the second and third stepped portions 90, 92run in opposite directions. For example, the second stepped portion 90may be provided with left-hand threads while the third stepped portion92 may be provided with right-hand threads, or vice versa. Thethrough-bore 86 also includes an end portion 94 adjacent to thecompressor apex 80 that has hexagonally-shaped internal walls (i.e., ahex recess) that are configured to receive a tool for tightening thecompressor wheel 28 on the threaded end 31 of the shaft 24. A toolpathway 96 extends along the centerline 30 between the third steppedportion 92 and the end portion 94. The tool pathway 96 provides toolaccess to the set screw 82, which prevents the compressor wheel 28 frombecoming over-tightened (i.e., over torqued) on the threaded end 31 ofthe shaft 24. As a result, the turbine apex 64 and/or the compressorapex 80 are unobstructed by a nut 74, hub 52, or other fastener. Itshould be appreciated that this arrangement may be reversed where thecompressor wheel 28 is welded to the shaft 24 and the turbine wheel 26is connected to the shaft 24 by set screw 82 and threaded connection 84.Alternatively, both the turbine wheel 26 and the compressor wheel 28 maybe connected to the shaft 24 via respective set screws 82 and threadedconnections 84.

A method of constructing the turbocharger 20 described above is alsoprovided. The method includes the steps of: machining a turbine wheel 26having a plurality of turbine blades 40, machining a compressor wheel 28having a plurality of compressor blades 48, creating leading edges 42,42′ on the plurality of turbine blades 40 and the plurality ofcompressor blades 48, and performing a finishing operation on theturbine wheel 26 and/or the compressor wheel 28 to form apexes 64, 80where the leading edges 42, 42′ converge. The finishing operation mayinclude removing a nut 74, hub 52, or other manufacturing/machiningfixture from the turbine or exhaust wheel 50 and/or the compressor orintake wheel 72 and extending the leading edges 42, 42′ towards acenterline 30 of the turbine wheel 26 and/or the compressor wheel 28. Asan alternative to machining the turbine wheel 26 and the compressorwheel 28, the turbine wheel 26 and the compressor wheel 28 can be cast,forged, or milled into the appropriate shape.

Optionally, the method may include the additional step of mounting theturbine wheel 26 and/or the compressor wheel 28 to a shaft 24 using awelding operation so that the apexes 64, 80 are unobstructed by a nut74, hub 52, or other fastener. Alternatively, the method may includeadditional steps of mounting the turbine wheel 26 and/or the compressorwheel 28 to a shaft 24 using a countersunk set screw 82 so that theapexes 64, 80 are unobstructed by a nut 74, hub 52, or other fastener.In accordance with this method of attachment, the set screw 82 isthreaded into the third stepped portion 92 of the through-bore 86 of thecompressor wheel 28. The threaded end 31 of the shaft 24 is thenthreaded into the second stepped portion 90 of the through-bore 86. Atool (such as a hex tool) is inserted into the end portion 94 and thetool pathway 96 of the through-bore 86 to set the depth of the set screw82 in the third stepped portion 92 of the through-bore 86. A larger hextool (e.g., an Allen key) is inserted into the end portion 94 of thethrough-bore 86 to rotate the compressor wheel 28 relative to the shaft24 until the threaded end 31 of the shaft 24 tightens against the setscrew 82. Advantageously, this attachment mechanism between thecompressor wheel 28 and the shaft 24 is easy to loosen/disassemble, evenafter extended periods of turbocharger use. This is an improvement overexisting designs, where the high-speed rotation of the compressor wheel28 during turbocharger operation over-tightens (i.e., over-torques) thecompressor wheel 28 on the threaded end 31 of the shaft 24 making itdifficult to disassemble. The set screw 82 in the subject design stopsfurther tightening of the compressor wheel 28 on the threaded end 31 ofthe shaft 24 during use. The set screw 82 also prevents over-torqueingof the compressor wheel 28 on the shaft 24 during or after assembly,which can bend the shaft 24 and create wobble in the turbocharger 20 anddamage the bearing pack 35 and/or the turbocharger 20.

Eliminating the nut 74 and/or hub 52 on both the turbine or exhaustwheel 50 and the compressor or intake wheel 72 greatly improves fluidflow and in-turn increases the potential horsepower and efficiency ofthe turbocharger 20. This manufacturing change is applicable to allwheel sizes, frame sizes, and area/radius (A/R) combinations for allturbocharger applications. The result is a dual apex turbocharger 20with decreased weight and increased speed capability.

FIGS. 12 and 13 illustrate an alternative design for a compressor wheel28″ of the turbocharger 20. The compressor wheel 28″ includes aplurality of compressor blades 48″ that extend from an exducer plate 98″at a trailing end 58″ of the compressor wheel 28″. The exducer plate 98″has a disc-like shape and defines an outer circumference 60″ of thecompressor wheel 28″. The compressor blades 48″ have leading edges 42″that converge at a compressor apex 80″ located at a leading end 56″ ofthe compressor wheel 28″. The compressor apex 80″ is aligned with acenterline 30″ of the compressor wheel 28″. The leading edges 42″ of thecompressor blades 48″ extend helically from an inboard point 66″ to anoutboard point 68″. In the illustrated example, the inboard points 66″of the leading edges 42″ touch one another and form a pointed shape atthe compressor apex 80″. In other words, the leading edges 42″ of thecompressor blades 48″ intersect at the compressor apex 80″. Because thecompressor apex 80″ is pointed and free of a tool interface, the flowcharacteristics and associated performance of the compressor wheel 28″is enhanced. As will be explained in greater detail below, the exducerplate 98″ includes one or more through bores 100″ to facilitateinstallation and removal of the compressor wheel 28″ relative to theshaft 24. The through bores 100″ extend through the compressor wheel 28″at locations that are offset (i.e., radially spaced) from the centerline30″. Of course, it should be appreciated that the compressor wheel 28″shown in FIG. 12 includes an internally threaded bore much like the bore86 of the compressor wheel 28 shown in FIG. 10, except that theinternally threaded bore in the compressor wheel 28″ shown in FIG. 12may or may not extend all the way to the leading end 56″ of thecompressor wheel 28″.

FIG. 13 illustrates a backing plate 102″, which is a sub-component ofthe housing 22 shown in FIG. 1, which is sometimes referred to as the“center housing rotation assembly” or “CHRA.” The backing plate 102″ hasa disc-like shape and includes a center hole 104″ that receives aportion of the shaft 24. The backing plate 102″ may also include acircular depression 106″ that receives a portion of the exducer plate98″ of the compressor wheel 28″. During operation of the turbocharger20, the backing plate 102″ remains stationary while both the shaft 24and the compressor wheel 28″ rotate relative to the backing plate 102″.The backing plate 102″ further includes one or more holes 108″ thatalign with the through bores 100″ in the exducer plate 98″ of thecompressor wheel 28″ when the compressor wheel 28″ is rotated to apredefined angular position. This allows for the insertion of one ormore fixation members 110″, such as dowel pins, set screws, otherfasteners, or a tool, into both the holes 108″ in the backing plate 102″and the through bores 100″ in the compressor wheel 28″ to temporarilylock rotation of the compressor wheel 28″ relative to the backing plate102″, thus creating a temporary fixation mechanism between thecompressor wheel 28″ and the housing 22. Although other configurationsare possible, in the illustrated example, the holes 108″ in the backingplate 102″ and the through bores 100″ in the compressor wheel 28″ arearranged 180 degrees apart from one another and have equal diameters.Additionally, the holes 108″ in the backing plate 102″ and/or thethrough bores 100″ in the compressor wheel 28″ may be internallythreaded to accept fasteners as the fixation members 110″.

Manufacturers or service technicians can grasp the other end of theshaft 24 and turn it clockwise or counter-clockwise to either tighten orloosen the compressor wheel 28″ from the shaft 24. This design andassociated assembly/disassembly process allows for easy installation andremoval of the compressor wheel 28″ from the shaft 24 withoutcompromising or damaging the compressor blades 48″ or other parts of thecompressor wheel 28″. It also eliminates the need for a nut, nose, orother tool interface at the leading end 56″ of the compressor wheel 28″;however, it should be appreciated that this configuration is applicableto both nose-less compressor wheels and compressor wheels that include anose at the leading end.

As shown in FIG. 14, the compressor wheel 28″ illustrated in FIG. 12 canalternatively be installed on and removed from the shaft 24 using a tool112″. The tool 112″ includes two posts 114″ that are configured (i.e.,have a size, shape, and spacing) to be received in the two through bores100″ in the exducer plate 98″ of the compressor wheel 28″ in slidingengagement. The tool 112″ also has a tool body 116″ with a center point118″ that is bisected by the centerline 30″ when the tool 112″ isbrought into alignment with the compressor wheel 28″. A socket interface120″, positioned at a center point 118″ of the tool 112″, extends intothe tool body 116″ and is configured to couple the tool 112″ to a wrenchor breaker bar (not shown). This allows the tool 112″ to be rotatedrelated to the shaft 24 and exert a rotational force to the compressorwheel 28″ without applying any pressure of the compressor blades 48″.Although other configurations are possible, in the illustrated example,the through bores 100″ in the compressor wheel 28″ and the posts 114″ onthe tool 112″ are arranged 180 degrees apart from one another and havesubstantially equal diameters.

When the posts 114″ on the tool 112″ are inserted into the through bores100″ in the compressor wheel 28″, the tool 112″ and the compressor wheel28″ are temporarily locked in rotation with each other. Manufacturers orservice technicians can hold/clamp the shaft 24 in place and turn thetool 112″ in a first (e.g. clockwise) direction and a second (e.g.,counter-clockwise) direction to either thread (i.e., tighten) orunthread (i.e., loosen) the compressor wheel 28″ from the shaft 24. Thisdesign and associated assembly/disassembly process allows for easyinstallation and removal of the compressor wheel 28″ from the shaft 24without compromising or damaging the compressor blades 48″ or otherparts of the compressor wheel 28″. It also eliminates the need for anut, nose, or other tool interface at the leading end 56″ of thecompressor wheel 28″; however, it should be appreciated that thisconfiguration is applicable to both nose-less compressor wheels andcompressor wheels that include a nose at the leading end.

FIGS. 15 and 16 illustrate an alternative design for a compressor wheel28″ and associated tool 112′″. The compressor wheel 28″ includes aplurality of compressor blades 48″ that extend from an exducer plate 98″at a trailing end 58′ of the compressor wheel 28′. The exducer plate 98′has a disc-like shape and defines an outer circumference 60′″ of thecompressor wheel 28′. The compressor blades 48″ have leading edges 42″that converge at a compressor apex 80′″ located at a leading end 56″ ofthe compressor wheel 28′. The compressor apex 80′″ is aligned with acenterline 30′″ of the compressor wheel 28′. The leading edges 42″ ofthe compressor blades 48″ extend helically from an inboard point 66″ toan outboard point 68′. In the illustrated example, the inboard points66″ of the leading edges 42″ touch one another and form a pointed shapeat the compressor apex 80′″. In other words, the leading edges 42″ ofthe compressor blades 48″ intersect at the compressor apex 80′″. Becausethe compressor apex 80′″ is pointed and free of a tool interface, theflow characteristics and associated performance of the compressor wheel28″ is enhanced. The exducer plate 98″ includes three through bores100′″ to facilitate installation and removal of the compressor wheel 28″relative to the shaft 24. The through bores 100′″ extend through thecompressor wheel 28″ at locations that are offset (i.e., radiallyspaced) from the centerline 30′″. Of course, it should be appreciatedthat the compressor wheel 28″ shown in FIG. 15 includes an internallythreaded bore much like the bore 86 of the compressor wheel 28 shown inFIG. 10, except that the internally threaded bore in the compressorwheel 28″ shown in FIG. 12 may or may not extend all the way to theleading end 56″ of the compressor wheel 28′.

As shown in FIG. 16, the compressor wheel 28″ illustrated in FIG. 15 canbe installed on and removed from the shaft 24 using tool 112′″. The tool112′ includes three posts 114′″ that are configured (i.e., have a size,shape, and spacing) to be received in the three through bores 100′″ inthe exducer plate 98′ of the compressor wheel 28″ in sliding engagement.Like in the other design, the tool 112′″ has a tool body 116′″ with acenter point 118′″ that is bisected by the centerline 30′ when the tool112′″ is brought into alignment with the compressor wheel 28′. A socketinterface 120′″ is positioned at a center point 118′″ of the tool 112′″,extends through the tool body 116′″, and is configured to couple thetool 112′″ to a wrench or breaker bar (not shown). This allows the tool112′″ to be rotated related to the shaft 24 and exert a rotational forceto the compressor wheel 28′ without applying any pressure of thecompressor blades 48′. Although other configurations are possible, inthe illustrated example, the through bores 100′″ in the compressor wheel28″ and the posts 114′″ on the tool 112′″ are arranged 120 degrees apartfrom one another and have substantially equal diameters.

Like in the previous design, when the posts 114′″ on the tool 112′″ areinserted into the through bores 100′ in the compressor wheel 28′, thetool 112′″ and the compressor wheel 28″ are temporarily locked inrotation with each other. Manufacturers or service technicians canhold/clamp the shaft 24 in place and turn the tool 112′″ in a first(e.g. clockwise) direction and a second (e.g., counter-clockwise)direction to either thread (i.e., tighten) or unthread (i.e., loosen)the compressor wheel 28″ from the shaft 24. This design and associatedassembly/disassembly process allows for easy installation and removal ofthe compressor wheel 28″ from the shaft 24 without compromising ordamaging the compressor blades 48″ or other parts of the compressorwheel 28″. It also eliminates the need for a nut, nose, or other toolinterface at the leading end 56″ of the compressor wheel 28′″; however,it should be appreciated that this configuration is applicable to bothnose-less compressor wheels and compressor wheels that include a nose atthe leading end. The designs disclosed herein advantageously providemore power using the same footprint. Because output can be increasedwithout increasing the frame size and A/R of the housing 22, the subjectdisclosure is particularly useful when there are space limitations onthe packaging dimensions of the turbocharger 20 (e.g., where theturbocharger 20 fits between the cylinder banks of the internalcombustion engine) or in motorsports applications with classrestrictions and rules that limit wheel size and other size dimensionsof the turbocharger 20.

Many modifications and variations of the subject matter disclosed hereinare possible in light of the above teachings and may be practicedotherwise than as specifically described while within the scope of theappended claims. It should be appreciated that variations of thedisclosed designs are possible without completely eliminating the hexnut 74 or the hub 52. For example and without limitations, the size ofthe nut 74 or hub 52 may be reduced and/or the nut 74 or hub 52 may beconed to form the apexes 64, 80.

What is claimed is:
 1. A forced induction device for an internalcombustion engine, comprising: a shaft extending co-axially about acenterline; a compressor wheel threadably mounted to the shaft; at leastone through bore extending through the compressor wheel at a locationthat is offset from the centerline of the shaft; and a tool including atleast one post that is configured to be received in the through bore inthe compressor wheel so as to temporarily lock the tool in rotation withthe compressor wheel and allow the compressor wheel to be rotatedrelative to the shaft during installation and removal of the compressorwheel.
 2. The forced induction device as set forth in claim 1, whereinthe compressor wheel has a plurality of blades with leading edges thatconverge at an apex that is aligned with the centerline of the shaft. 3.The forced induction device as set forth in claim 2, wherein the leadingedges of the plurality of blades extend helically from an inboard pointto an outboard point.
 4. The forced induction device as set forth inclaim 3, wherein the inboard points of the leading edges touch oneanother and form a pointed shape at the apex.
 5. The forced inductiondevice as set forth in claim 3, wherein the shaft has a radius and theinboard points of the leading edges are positioned closer to thecenterline than the radius of the shaft.
 6. The forced induction deviceas set forth in claim 1, wherein the compressor wheel includes anexducer plate and the at least one through bore in the compressor wheelextends through the exducer plate at a location that is radially spacedfrom the centerline of the shaft.
 7. The forced induction device as setforth in claim 6, wherein the tool includes a socket interface,positioned at a center point of the tool, that is configured to couplethe tool to a wrench, ratchet, Allen key, or breaker bar.
 8. The forcedinduction device as set forth in claim 6, wherein the compressor wheelincludes two through bores that are arranged 180 degrees apart from oneanother and wherein the tool includes two posts that are arranged 180degrees apart from one another and are configured to be received in thethrough bores in the compressor wheel.
 9. The forced induction device asset forth in claim 6, wherein the compressor wheel includes threethrough bores that are arranged 120 degrees apart from one another andwherein the tool includes three posts that are arranged 120 degreesapart from one another and are configured to be received in the throughbores in the compressor wheel.
 10. The forced induction device as setforth in claim 1, further comprising: a turbine wheel mounted to theshaft; and a housing that includes a turbine section for housing theturbine wheel and a compressor section for housing the compressor wheel,wherein the shaft is rotatably supported by the housing.
 11. The forcedinduction device as set forth in claim 10, wherein both the turbinewheel and the compressor wheel have a hub-less configuration and eachhave an apex that is unobstructed by a nut or other fastener.
 12. Acompressor wheel, comprising: a body extending along a centerlinebetween a leading end and a trailing end, the body having an outercircumference that is radially spaced from the centerline by acompressor radius; an exducer plate positioned at the trailing end ofthe body; a plurality of compressor blades positioned on the body, theplurality of compressor blades having leading edges that converge at acompressor apex located at the leading end of the body, wherein thecompressor apex is aligned with the centerline; and at least one throughbore, extending through the exducer plate at a location that is offsetfrom the centerline and configured to receive a tool.
 13. The compressorwheel as set forth in claim 12, wherein the tool includes a socketinterface that is configured to couple the tool to a wrench, ratchet,Allen key, or breaker bar.
 14. The compressor wheel as set forth inclaim 13, wherein the at least one through bore includes two throughbores that are arranged 180 degrees apart from one another and whereinthe tool includes two posts that are arranged 180 degrees apart from oneanother and are configured to be received in said through bores in saidexducer plate.
 15. The compressor wheel as set forth in claim 13,wherein the at least one through bore includes three through bores thatare arranged 120 degrees apart from one another and wherein the toolincludes three posts that are arranged 120 degrees apart from oneanother and are configured to be received in said through bores in saidexducer plate.
 16. The compressor wheel as set forth in claim 12,wherein the leading edges of the plurality of compressor blades extendhelically from an inboard point to an outboard point and the inboardpoints of the leading edges of the compressor blades touch one anotherand form a pointed shape at the compressor apex.
 17. The compressorwheel as set forth in claim 12, wherein the body of the compressor wheelhas a threaded bore with a radius that is sized to receive a shaft,wherein the leading edges of the plurality of compressor blades extendhelically from an inboard point to an outboard point, and wherein theinboard points of the leading edges of the compressor blades arepositioned closer to the centerline than the radius of the threadedbore.
 18. A method of constructing a forced induction device, the methodcomprising the steps of: machining a compressor wheel having a pluralityof compressor blades; creating leading edges on the plurality ofcompressor blades; performing a finishing operation on the compressorwheel to form an apex where the leading edges converge; temporarilylocking the compressor wheel in rotation with a tool that includes oneor more posts that are received in one of more through bores in thecompressor wheel; and mounting the compressor wheel to a shaft byinserting the shaft into an internally threaded bore in the compressorwheel and rotating the compressor wheel relative to the shaft in a firstdirection using the tool to thread the shaft into the internallythreaded bore of the compressor wheel.
 19. The method as set forth inclaim 18, further comprising the steps of: removing the compressor wheelfrom the shaft by rotating the compressor wheel relative to the shaft ina second direction that is opposite from the first direction using thetool to unthread the shaft from the internally threaded bore in thecompressor wheel while the compressor wheel.
 20. The method as set forthin claim 18, further comprising the step of: mounting a turbine wheel tothe shaft at an opposite end of the shaft relative to the compressorwheel.